Temperature measurement system comprising a resonant mems device
AssigneeImec
InventorsXavier Rottenberg, Roelof Jansen, Hendrikus Tilmans
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Abstract
A micromechanical resonator device and a method for measuring a temperature are disclosed. In one aspect, the device has a resonator body, an excitation module, a control module, and a frequency detection module. The resonator body is adapted to resonate separately in at least a first and a second predetermined resonance state, selected by applying a different bias, the states being of the same eigenmode but having a different resonance frequency, each resonance frequency having a different temperature dependence. The micromechanical resonator device may have a passive temperature compensated resonance frequency.
Claims19
A micromechanical resonator device for measuring a temperature, the device comprising:
- a resonator body;
- an excitation element associated with the resonator body and configured to excite the resonator body;
- and
- a control element connected to the excitation element and configured to control the excitation element to excite the resonator body,
- wherein the resonator body is configured to resonate in a first and a second predetermined resonance state, the first and second resonance states being of the same eigenmode but having different resonance frequencies, the resonance frequencies having a different temperature dependency,
- wherein the control element is configured to supply to the excitation element separately a first bias to excite the resonator body into the first resonance state, and a second bias to excite the resonator body into the second resonance state,
- wherein the micromechanical device further comprises:
- a frequency detection element associated with the resonator body and configured to detect a frequency at which the resonator body resonates, and
- a temperature determination element connected to the frequency detection element and configured to determine a temperature of the micromechanical resonator device from a first frequency, detected while the resonator body is in the first resonance state, and a second frequency, detected while the resonator body is in the second resonance state.
A method of determining a temperature of a micromechanical resonator device, the device comprising a resonator body configured to resonate in a first and a second predetermined resonance state, the first and second resonance states being of the same eigenmode but having different resonance frequencies, the resonance frequencies having a different temperature dependency, the method comprising:
- applying a first bias to excite the resonator body into the first resonance state and measuring a first frequency while the resonator body is in the first resonance state;
- applying the second bias to excite the resonator body into the second resonance state and measuring a second frequency while the resonator body is in the second resonance state;
- and
- determining a temperature of the micromechanical resonator device using the measured first and second frequency.
A micromechanical resonator device having a predetermined resonance frequency (fres), the device comprising:
- a resonator body suspended above and anchored to a substrate and configured to resonate in a predetermined resonance state at the predetermined resonance frequency (fres);
- an excitation element configured to excite the resonator body, the excitation element and the resonator body being separated from each other and together forming a transconductive structure;
- a control element connected to the excitation element and configured to apply a predetermined bias (V, NI) to the excitation element to excite the resonator body into the predetermined resonance state;
- wherein the resonance state is a mechanical vibration mode parallel to the plane of the substrate, the material of the resonator body and the material of the substrate are selected such that the ratio of the coefficient of thermal expansion of the substrate material (CTEsub) and the coefficient of thermal expansion of the resonator body material (CTEbar) is larger than 1.0,
- wherein the transconductive structure has a transconductance with a predetermined temperature dependency which is defined by a set of parameters, the set of parameters comprising the material of the resonator body, the material of the substrate, the geometry of the resonator device (W0, d0), and the predetermined bias (V, NI), wherein the set of parameters being selected such that at a predetermined temperature (T0), the predetermined temperature dependency of the transconductance compensates the intrinsic temperature dependence of the resonance frequency (fres).
Dependencies are inferred from the claim text.